Gaseous glow indicator tube formed on a substrate with a plurality of insulating layers

ABSTRACT

A GASEOUS GLOW INDICATOR TUBE INCLUDING METHOD OF MANUFACTURING AND AGING IN WHICH THE ELEMENTS OF THE INDICATOR ELECTRODES ARE ARRANGED IN A SINGLE PLANE BY PLATING CONDUCTING SEGMENTS ON A BASE INSULATING PLATE WHICH ALSO CARRIES A PLURALITY OF ELEMENT ENERGIZING ELECTRODES. THE VARIOUS ELEMENTS OF THE INDICATOR ELEMENTS ARE INDIVIDUALLY CONNECTED TO THE ENERGIZING ELECTRODES BY STRIP CONDUCTORS WHICH ARE   MOUNTED ON A LAYER OF INSULATION WHICH OVERLIES THE ENERGIZING ELECTRODES. ANODE ELECTRODES ARE MOUNTED ADJACENT THE INDICATOR ELECTRODES AND ARE CONNECTED TO ANODE ENERGIZING LEADS SO AS TO SELECTIVELY ENERGIZE VARIOUS INDICATIONS. A METHOD FOR AGING THE GASEOUS GLOW INDICATOR IS ALSO DISCLOSED.

United States Patent [72] inventors SaburoUemura;

Yuzuru Yanagisawa. Kanagawa-ken, Japan Appl. No. 741,668

3,327,154 6/1967 Bowerman 3,346,759 10/1967 Hardwick.....................

Primary ExaminerRoy Lake 1 [22] Filed July 1,1968 [45] Patented June 28,197]

Assignee Sony Corporation Tokyo, Japan [32] Priority July 7, 1967 Assistant Examiner-E. R. La Roche 33] Japan Att0rneyHill, Sherman, Meroni, Gross and Simpson 3 l 1 42/43782 ABSTRACT: A gaseous glow indicator tube including method [541 0N of manufacturing and aging in which the elements of the in- INSULATING LAYERS dicator electrodes are arranged in a slngle plane by plating 6 CI 3 D in n conducting segments on a base insulating plate which also carraw 3 ries a plurality of element energizing electrodes. The various elements of the indicator elements are individually connected to the energizing electrodes by strip conductors which are mounted on a layer of insulation which overlies the energizing electrodes. Anode electrodes are mounted adjacent the indicator electrodes and are connected to anode energizing leads so as to selectively energize various indications. A method for aging the gaseous glow indicator is also disclosed.

0 1 .l k 9 M 16 103 7 5 .1" l mm m W n U m m m m M m0 u m m m m m m0 u "2 u H u n u u h u u 9 u u m n n 1. L m t C U o U h F PATENTEDJUNZBIQTI 3588-571 saw 1 or 2 INVENI'OR. SABUPO U E M URA Y Z YANAQISAWA M GASEOUS GLOW INDICATOR TUBE FORMED ON A SUBSTRATE WITH A PLURALITY OF INSULATING LAYERS BACKGROUND OF THE INVENTION 1. Field of the Invention The invention relates in general to gaseous glow indicator tubes and in particular to a novel gaseous glow indicator tube and method of manufacturing and aging such tube.

2. Description of the Prior Art Gaseous glow indicator tubes which include a plurality of indicator cathode units mounted inside of a transparent envelope for providing displays of numerals, symbols, letters or the like, have been commercially available. For example, the so-called Nixie Tube" is a tube which utilizes a transparent envelope that contains an anode electrode and a plurality of cathode glow indicator electrodes aligned in a stack one above the other. Such tubes require substantial thickness because the electrode indicator units are placed one above the other and a number of electrodes are used and are relatively expensive to manufacture. Such tubes are difficult to manufacture and are illegible unless the observer is directly in front of the indicator tube. This is because the gaseous glow indicator electrodes are numerous and are mounted in different planes.

SUMMARY OF THE INVENTION The present invention relates to a gaseous glow indicator tube which has a plurality of indicator cathode units mounted inside of a transparent envelope with the indicator electrode units mounted in substantially the same plane. The indicator electrode units may be fonned with thin film techniques and each electrode is connected to energizing leads by printed circuit or thin film conductors to obtain an efficient, inexpensive and compact unit. Mesh screen anode electrodes are attached over the indicator electrode units and are connected to energizing electrodes by thin film or printed circuit techniques.

The printed circuit indicator assembly is placed into a transparent envelope and sealed with a suitable ionizable gas such as neon with a small amount of mercury so as to cause the cathodes to glow upon the suitable energization of a cathode electrode and an anode electrode.

An aging apparatus and method is provided for rapidly aging a number of cathode elements by applying energizing signals on a time sequence bases which provides a higher than normal operating potential so as to rapidly age the indicators.

Other objects, features and advantages of the present invention will be readily apparent from the following detailed description of certain preferred embodiments thereof taken in conjunction with the accompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS FIGS. 1A through 1F illustrate the method of fabricating a glow indicator tube in accordance with this invention;

FIG. 2 illustrates a testing apparatus and method for testing a glow indicator tube according to this invention; and

FIG. 3 illustrates wave forms I, through t, which are used in the apparatus of FIG. 2 to test a gaseous glow indicator tube according to this invention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention relates to a glow indicator apparatus made with printed circuit techniques and results in a very thin unit. The number of weld and solder junctions are substantially reduced in the present structure and the symbols, letters or numerals appear very clear because the electrode segments which are caused to glow when energized are mounted in the same plane.

FIG. 2 illustrates a planar board 1 of insulating material upon which the individual indicator electrode units are to be attached by plating processes with suitable energizing leads. The particular unit being illustrated in FIGS. 1 comprises a element indicator as illustrated in FIG. 1F It is to be realized,

of course, that any number of elements may be placed in the indicator device and they need not be placed in a horizontal line but may be mounted at any position as, for example, vertically or in a matrix.

Each of the numerals 1 through 0 illustrated in FIG. 1F may be constructed by using seven indicator elements with three of the indicator elements mounted horizontally and symmetrically on the indicator and with four of the indicator electrode elements mounted vertically on two opposite sides of the three elements.

By selectively energizing various of the indicator electrode elements, all of the numerals 1 through 0 may be produced. An additional period or decimal element is also mounted to each of the numeral electrode element groups to provide a period or decimal where desired. FIG. 1A illustrates a rectangular insulating base plate 1 which might be formed of aluminum oxide, for example, of a purity exceeding 92 percent. A plurality of indicator units 3, through 3,, are formed on the base plate 1 by suitable thin film techniques, as for example, printing and baking. For example, molybdenum and manganese may be sintered in a hydrogen or ammonium gas atmosphere at about 1,100 C. to produce a metallized plating. The sintered materials are then plated with nickel and subjected to diffusion of hydrogen gas at about 780 C. The nickel plating prevents oxidation of molybdenum and manganese by the hydrogen gas diffusion and eliminates the necessity of treatment in a nonoxidizing atmosphere in later manufacturing processes.

Each of the indicator units 3 comprises three horizontal electrode segments 2,, at the center of the plate 1, 2, above segment 2, and 2, below the segment 2,. On the left edge of these segments relative to FIG. 1B are formed the vertical segments 2, and 2,. On the right edge of the horizontal segments are formed the vertical segments 2, and 2 A period or decimal segment 2, is formed adjacent the electrode 2,. Conductive segments 5, through 5, are connected to each of the indicator electrode segments 2, through 2,. Along the upper edge of the plate 1 are formed four energizing conductors 4, through 4 and along the lower edge are formed four more energizing electrodes 4, through 4,. The strip 5, is connected to the conductor 4, and the strip 5, is connected to the conductor 4,. After the conductors 4, through 4, and the electrodes and connector strips 2, through 2, and 5, through 5, are formed on the board, an insulating layer 6 is formed over the entire surface of the base plate 1 except on the indicator electrode segments 2, through 2, and openings 7, through 7 are left for each of the indicator units 3, through 3,,,. In addition, small windows 8, to 8, and 8, to 8, are left. Also, small apertures 5, to 5, and 5, t9 5, are formed at the free ends of the strip conductors 5. The apertures 8, to 8, and 8, to 8, and apertures 5, to 5, and 5, to 5, allow the electrode segments to be connected to the leads 4, through 4, and 4, through 4,, respectively. The insulating layer 6 may be formed by the silk screen process in the same manner as the electrode segments 2 and the leads 4 and strips 5 are formed. The insulating layer 6 may be formed, for example, of"glass frit 08190" manufactured by the Du Pont Corporation. The insulating layer 6 may be formed by coating the glass frit on the base plate 1 two or three times and then drying it in the air at C. to C. for 10 to 15 minutes. The insulating layer is further heated in an oxidizing atmosphere of approximately 300 C. for about 15 minutes to disperse a binder contained in the glass frit and thereafter is exposed to nitrogen gas at about 850 C. for about 10 minutes in a quartz glass furnace to bake the glass frit.

The connecting leads 9, to 9, and 9, to 9, are then formed over the insulating layer 6 between the small apertures 5, and 8,, between 5, and 8,, between 5, and 8,, between 5, and 8,, between S, and 8 and between 5, and 8,, as shown in FIG. 1D. These connecting leads may be formed by silk screen printing techniques as, for example, by using a mixture of silver and palladium powder with glass frit. After the printing of the leads 9, the printed mixture is dried in the air at 100 C.

to 225 C. for approximately 10 to 15 minutes and is then heated in an oxidizing atmosphere of 300 C. or so for about 15 minutes to disperse a binder in the mixture. It is then exposed to nitrogen gas for about 10 minutes in a quartz glass furnace maintained at 760 C. to effect baking of the printed mixture.

The second insulating layer 10 is formed over the insulating layer 6 to cover the connecting leads 9, but the windows 7, to 7, are again left open. The insulating layer is formed in the same manner as the layer 6 by fusing the glass frit over the layer 6, after which the unit is held at 100 C. to 120 C. in the air for 10 to minutes before placing it in an oxidizing atmosphere at about 360 C. for about 15 minutes to disperse the binder in the glass frit. Nitrogen gas is then passed over the unit in a quartz glass furnace at about 850 C. for 10 minutes to bake the insulating layer 10. The electrode segments 2, through 2,, may be plated with nickel before the formation of the insulating layer 10 or they may be coated with a nickel layer after the formation of the insulating layer 10. The nickel layer may be formed by electrolytic or nonelectrolytic plating, and it is desirable that the electrode segments 2 be covered with a nickel layer thick enough to act as cathodes and that the nickel be of a purity in excess of 99.9 percent.

After the formation of the insulating layer 10, external leads 11, to 11,, are connected to the segment selecting leads 4, to 4 The leads 11, to 11,, are welded into one end of the base plate 1 at the positions corresponding to the ends of leads 4, to 4,, so that they make electrical contact therewith.

Mesh screen anode electrodes 12, to 12, are attached to the base plate 1 over each of the individual display units 3, through 3,, and are connected to external leads M, to 14, which extend through the base plate 1. Insulating partition walls or supports 13 are spaced on either side ofeach of the indicator units 3 and may be constructed, for example, of mica or other similar insulating material. An insulating layer of glass frit or other similar material may be formed on the back of the base plate 1 in the manner as previously described.

The completed electrode assembly is placed into a transparent envelope, for example, a glass tube 15, as shown in FIG. 1F. The envelope 15 is filled with an ionizable gas such as neon and a small quantity of mercury and sealed. By applying a voltage potential to a particular external lead 141, to 141, of an anode electrode and to different external leads 11, to 11,, which supply electrical potential to the segments 2, through 2 various segments may be caused to glow.

To assure that the indicator electrodes 2, through 2,, produce uniform glow over their entire length, it is desirable to age or activate the electrodes.

FIG. 2 illustrates apparatus to accomplish this. The device illustrated allows current to be sequentially applied between anode electrodes and each of the indicator electrodes of each display unit to repeat the discharge of current between them on a timedivisional basis.

In the case of a gaseous glow indicator tube 16, which has, for example, fifteen display units, the electrode segment selecting leads are connected together through resistors R, through R with the other side of each resistor connected to ground. The anode electrodes 12, to 12,, are connected to a booster circuit 17 which receives an input from an oscillator 18. A counter circuit 19 is connected between the oscillator 18 and the booster circuit 17 to distribute the output of the oscillator to the various leads 14, through 1d,, to respectively energize the anode screens 12, through 12, The counter circuit 19 distributes the output pulses of the oscillator 18 to the leads 14, to 1d,, so that each of the indicator units are sequentially turned on. For example, a wave-shape 1,, illustrated in FIG. 3, is supplied to lead M, to energize the anode electrode 12,, and wave-shape t, which is slightly delayed from the wave-shape t, is supplied to the lead 14,, etc. The pulses in FIG. 3 might, for example, be 100 microseconds in width and 1.5 milliseconds apart.

It is seen that this invention employs printing circuit techniques for the manufacture of display discharge indicators and substantially reduces the amount of welding required. F or example, in the conventional Nixie Tube", 516 welding points are required for connecting the electrodes of the indicator. In the present invention, an indicator tube produced according to this invention requires only 30 points of welding or substantially less than 10 percent as many as required in the Nixie Tube. The insulating layers 6 and 10 are formed by heating the base plate 1 coated with the glass frit at 300 C. in an oxidizing atmosphere to disperse the binder contained in the glass frit and by heating the base plate 1 at a temperature from 700 C. to 800 C. in an inert gas atmosphere to fuse the glass. This enables formation of the glass layers which form the insulating layers without oxidizing the metal of the electrodes or leads.

The base plate coated with glass frit may also be heated in a forming gas atmosphere to reduce lead contained in the glass to provide black insulating layers which enhances the contrast in color between the discharge glow of the electrodes and the insulating layers and allows easier interpretation of a number or symbol being displayed.

The aging apparatus illustrated in FIG. 2 allows units having 15 display units to be properly aged in about 15 minutes. Where each individual display unit is aged in a sequential fashion, a minimum time of about 5 minutes for each unit is required or a total of 75 minutes for 15 units. The unit of FIG. 2 allows 15 units to be aged in about 15 minutes for a saving of 60 minutes.

Although in the process described above, the connecting leads 9, to 9;, and 9,, to 9,, were formed after the insulating layer 6, it is to be realized that the selecting leads 4, to 4,, and the various strip conductors may be formed in various sequences to obtain the same result.

The insulating base plate 1 may be formed of glass, steatite or the like, if desired, rather than aluminum. When the base plate 1 is formed of ceramic, it is possible that the base plate may be blackened by mixing an oxide with the ceramic in the ratio of about 10 percent relative to the ceramic to provide an indicator tube of good contrast. it is also to be realized that the electrodes may be formed on convex or concave portions of the base plate which are aligned with the indicator units. This increases the distance between adjacent electrode segments and avoids undesirable discharge between adjacent electrode segments. This also reduces the possibility of short circuits between the electrodes due to sputtering caused by discharge and thus lengthens the life of the indicator tube.

The electrode segments may be formed of usual conductive materials other than molybdenum and manganese. For example, silver and palladium film, palladium film or gold and platinum film may be used. A silver-palladium film results in very stable connections.

When using silver-palladium film, it is coated on the base plate by printing techniques, dried in the air at a temperature of C. to C. for 10 to 15 minutes and is then heated in an electric furnace at about 750 C. for 45 minutes or so, thus hardening the film to provide the electrode segments.

Although the present invention has been described in connection with an indicator with individual units mounted in a row, it is to be realized that other arrangements of the indicator units may be made, such as in columns or in a matrix. Also, it is to be realized that a plurality of indicator units may be mounted in a single envelope.

Although minor modifications might be suggested by those versed in the art, it should be understood that we wish to embody within the scope of the patent warranted hereon all such modifications as reasonably and properly come within the scope of our contribution to the art.

We claim:

1. A gaseous glow indicator tube comprising:

a planar plate of insulating material;

a plurality of segmented electrode patterns formed on said plate;

a plurality of cathode leads corresponding to the number of segments in each pattern;

a portion of said cathode leads connected to a portion of said segmented electrode patterns;

each of said portion of cathode leads interconnecting all of the corresponding segments of said patterns;

an insulating layer formed over the portion of said cathode leads with apertures in register with each of said segmented electrode patterns;

additional apertures for connecting the remaining portion of said cathode leads to interconnect all the corresponding remaining portions of segments of said patterns;

anode electrodes for each pattern and mounted in spaced relation therewith;

a transparent sealed envelope enclosing said insulating plate, said insulating layer and said electrode structure; and

an ionizing gas in said sealed envelope.

2. A gaseous glow indicator tube according to claim 1 wherein each of said plurality of segmented electrode patterns includes seven segments in the shape of a figure eight.

3. A gaseous glow indicator tube according to claim 2 wherein each of said segmented electrode patterns includes an auxiliary electrode mounted adjacent the bottom of the eight.

4. A gaseous glow indicator tube according to claim 1 wherein said planar plate includes dark material to improve contrast.

5. A gaseous glow indicator tube according to claim 1 wherein the area of the plate is concave beneath each segment of said electrode pattern.

6. A gaseous glow indicator tube according to claim 1 wherein the area of the plate is convex beneath each segment of said electrode pattern. 

